Tooth decay and dental disease can be caused by bacterial action resulting from the formation of plaque about the teeth and/or the entrapment of food particles between the teeth and interstices therebetween. The removal of plaque and entrapped food particles reduces the incidence of caries, gingivitis, and mouth odors as well as generally improving oral hygiene. Conventional brushing has been found to be inadequate for removing all entrapped food particles and plaque. To supplement brushing, dental flosses and tapes have been recommended. The term "dental floss", as used herein, is defined to include both dental flosses, dental tapes and any similar article.
To improve the effectiveness and convenience of dental flosses, dental flosses combining a thin "floss" portion and a thickened "brush" portion, together with a threader have been developed. The brush portion, when drawn between tooth surfaces, has been found to provide an improved cleaning action which removes materials left by the floss portion, when used alone. The combination provides a substantially superior cleaning action. Such a device is described in U.S. Pat. No. 4,008,727, for example. The complexity of this product requires that each floss segment be individually manufactured and that the product be packaged as bundles of the individual, separate floss articles.
A continuous yarn having brush segments separated by thinner segments is disclosed in U.S. Pat. Nos. 4,008,727 and 4,142,538.
A problem arising in the manufacturing process of continuous floss brushes involves the application of coatings to the yarn. A variety of assemblies and methods are known for providing a yarn with a coating at spaced locations. For example, in one arrangement, a roller receives a coating from a supply, and provides a coating to the yarn as the yarn passes there over in contact with the roller. The roller can be formed with only a partial section of a cylinder, such that only intermittent portions of the yarn contact the roller as the roller rotates. However, such an arrangement has been unsatisfactory in providing an adequate coating to the yarn, particularly in high speed manufacturing assemblies, for example, in which the yarn is traveling at over 100 meters/min., possibly even as high as 160 meters/min.